1. Field of the Invention
The present invention relates to fluids for melting and/or preventing the formation or re-formation of ice on a surface, and more particularly, to deicing compositions for removing ice from the windshield of an automobile.
2. Brief Description of the Prior Art
The difficulties occasioned by the formation of ice on a surface are well known. The term "ice" as used herein refers generically to the various forms of frozen water which may be encountered on surfaces such as sidewalks, aircraft, automobile windshields, car doors and locks, roads and the like.
In the specific context of a deicing composition for use on automobile windshields, for example, the characteristics that are desired in the deicing composition are also well known. Among the more important of these characteristics are the ability to melt ice quickly, to inhibit its re-formation after a period of time, and to have a sufficiently low viscosity to "wet" the windshield fully without smearing or streaking, and the compatibility of the composition with the materials comprising the automobile's windshield and its immediate surroundings.
A number of deicing formulations have been developed over the years, and the art reflects a continuing effort to find a formulation which fully possesses each of the recited characteristics. Several deicing compositions have been developed containing monohydric alcohols to initially melt the ice on a windshield, polyhydric alcohols to inhibit the reformation of ice, and surfactants.
For example, one commercially available deicing product utilizes a composition including monohydric and polyhydric alcohols, a dye, about 1.5 percent by weight of water, and an alkyloxyalkyl sodium sulfate surfactant.
U.S. Pat. No. 3,245,912 to White discloses a deicing composition including monohydric alcohols, polyhydric alcohols, and from 0.25 to about 3 percent by weight of an alkylphenoxypolyethanoxyethanol surfactant. The monohydric alcohols fraction is preferably mostly isopropanol, and the reference discusses the previous commercial use of combinations of monohydric and polyhydric alcohols in deicing.
U.S. Pat. No. 4,235,637 to Singleton discloses an anti-foggant composition, as opposed to a deicing composition, which incorporates a lower alcohol, a lower polyhydric alcohol, and a surfactant or a mixture of anionic or nonionic surfactants such as contained in an IVORY liquid dishwashing detergent, for example, with starch granules for spraying onto mirrors and the like. The lower alcohol can be isopropyl alcohol, propyl alcohol, ethyl alcohol, or methyl alcohol, for example.
Japanese Application 63-077,987 discloses a foam composition for use in preventing the freezing over of windshields, for example. The composition contains lower alcohols such as methanol and isopropanol, hygroscopic polyhydric alcohols such as ethylene glycol and glycerol, and polyoxyethylene stearyl and cetyl ethers as surfactants for forming and maintaining the foam.
A liquid deicing formulation containing 30 percent of ethylene glycol, 70 percent of isopropanol, and 1-10 percent of nonionic surfactants based on the combined ethylene glycol and isopropanol is reported by Ushakova, Tr. Nauch.-Issled. Tekhnokhim. Inst. Byt. Obsluzhivaniya, No.6, 34-39(1965).
Japanese Application 71-16487 discloses a frost-preventing agent for car windshields and windows which comprises as a major component one or more glycols, an alcohol diluent, 2-ethoxyethanol and a surfactant for use as a wetting agent.
West German patent DE 3,208,219 A1 to Wack et al. discloses an anti-icing liquid for the windshield of an automobile which contains an "active substance" such as a citrate, phosphate, nitrilotriacetic acid or ethylenediaminetetraacetic acid in a concentration between 3 percent and the saturation concentration of the active substance in water, 0.01 to 5 percent of a (fluoro)surfactant for improved wetting of the windshield, 2-12 percent alcohol for improved wetting also, 5-30 percent of glycol(s), and 1-8 percent of a "solvent aid", with the remainder being water. Examples of suitable "solvent aids" include "toluene sulfonate, xylene sulfonate, cumene sulfonate or a derivative of an alkyl-substituted dicarboxylic acid such as an alkyl radical from C.sub.1 to C.sub.12 reacted with maleic anhydride."
The seemingly complete body of art relating to deicing compositions does not, however, appear to disclose or suggest the comparatively simple yet efficacious composition described below.